Method and apparatus for limiting equipment burden when penetrating a mixed or composite material structure including metal utilizing a hammer-drill

ABSTRACT

A method employing an apparatus in conjunction with a hammer-drill to penetrate composite metal and non-metal structure or structures including, for example, thick metal or rebar encountered during concrete, rock or masonry boring operations without requiring a change in drill equipment.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication Ser. No. 62/217,777, filed Sep. 11, 2015, entitled “METALCUTTING SDS MAX BIT,” the disclosure of which is expressly incorporatedby reference herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The invention described herein includes contributions by one or moreemployees of the Department of the Navy made in performance of officialduties and may be manufactured, used and licensed by or for the UnitedStates Government for any governmental purpose without payment of anyroyalties thereon. This invention (Navy Case 200,285) is assigned to theUnited States Government and is available for licensing for commercialpurposes. Licensing and technical inquiries may be directed to theTechnology Transfer Office, Naval Surface Warfare Center Crane, email:Crane CTO@navy.mil.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a method employing an apparatus inconjunction with a hammer-drill to penetrate thick metal and rebarencountered during concrete, rock or masonry boring operations(hereafter referred to as “rock drilling”) without requiring a change indrill equipment. Hammer-drills are recognized as the most efficient wayto bore into concrete, rock, or masonry (hereafter collectively referredto as “rock”) and are employed when the primary task is to penetratesuch materials. By employing the present invention, operators arerelieved of the necessity of carrying an additional drill or otherequipment in order to address metal should any be encountered duringrock drilling. Such an advantage will be particularly beneficial insituations where the transportation of a second drill, or otherequipment, would be undesirable. The additional weight of a seconddrill, or other equipment, would be particularly undesirable in certainmilitary operations or other operations in an austere environment.

On occasion, during rock drilling, metal plate or other inorganicmaterials are encountered, often unexpectedly, embedded in the rock.Neither the equipment nor bits in current use are capable of penetratingsignificant thicknesses of metal plate without great stress, damage ordestruction to equipment and passage of significant or undesirableduration of time in rock drilling. In existing technology, rock drillingequipment is removed from a hole and specific equipment is substitutedor exchanged to address drilling through different materials such as aplate, rebar, etc. Existing approaches have drawbacks, not the least ofwhich is a need to stop rock drilling and the time and logisticsassociated with exchanging or substituting equipment and then replacingand resuming rock drilling once the dissimilar material, e.g., inorganicobstacle, is overcome.

Hammer-drill equipment can be used with rock drilling relying on acombination of low-rpm torsional moment and a repetitive axial force topenetrate a target material. The repetitive axial force is known as a“hammer feature” as its effect is the same as a hammer striking the endof a masonry chisel. As the name suggests, drills with this featureoften achieve this effect by employing an internal hammer to strike anend of an inserted masonry bit. Typically, a masonry bit is a form oftwist bit milled from relatively soft steel with a hardened chisel pointbraised onto the bit's end forming the cutting edges. The hammeringmotion breaks up the rock at the point of contact between the chiselpoint and the material being drilled, while the rotating flutes removethe resultant debris. For “heavy duty” hammer drills, such as thoseemploying the Slotted Drive System (SDS) Max form factor bits, thehammer feature is always activated and cannot be disabled by the user.

Drill equipment associated with drilling into metal relies primarily onthe torsional moment applied to the drill bit to employ the bit'sgeometry and achieve a desired cutting action, while the axial forceprimarily keeps the bit in contact with the target material. The cuttingaction is the result of the bit's cutting edge being rotated while incontact with the surface being drilled. If such a bit is employed in adrill with the hammer function active while attempting to drill throughmetal, the bit will rebound from the hardened surface with each blow ofthe hammer. This will prevent the engagement of the cutting edge withthe surface and the loss of contact will result in the inability topenetrate the hardened material.

Existing steel cutting bits are not designed to be employed in a drillwith an active hammer feature, cut large diameter holes, or to routinelyencounter rock surfaces without rapidly dulling. Employing alternatemeans to penetrate the material so that drilling may resume, havecertain drawbacks making their employment undesirable. Cutting torchesrequire fuels, expendable rods or both and leave hot residue in the pathof the drilling equipment. Falling slag is a safety hazard associatedwith some types of existing approaches. Torches and energetic/explosivesystems cannot be used in all environments or scenarios. Theserestrictions are especially likely to be encountered underground orindoors.

Hammer-drilling equipment may be especially adapted for industrial orfixed site operations and the use of a specialized bit for penetratingthe inorganic obstacle allows the continued use of the safer equipment.Improved bits allow for drilling of holes in metal with hammer-drillingequipment even if the hammer function cannot be disabled. An exemplarybit can be designed to cut steel and other metal at low revolutions perminute (RPM) while allowing for some contact with the rock surfacebehind the steel without rapidly destroying the tool or negativelyaffecting the drill's hammer function. Use of this exemplary bit duringrock drilling allows the drilling to progress through steel and similarmaterials when encountered by simply changing the bit. Equipment canremain in place and torches and exothermic/energetic systems are nolonger required with embodiments of the invention. Exemplary aspects ofthe invention can also reduce time associated with drilling throughmixed materials and reduces the amount and types of equipment currentlynecessary to accomplish this task. These bits are designed for use onthe surface or inside the bore hole.

Additional features and advantages of the present invention will becomeapparent to those skilled in the art upon consideration of the followingdetailed description of the illustrative embodiment exemplifying thebest mode of carrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description of the drawings particularly refers to theaccompanying figures in which:

FIG. 1 shows an exemplary method of utilizing one embodiment of theinvention;

FIG. 2 shows an exemplary metal drilling system including a hammer drillsystem and exemplary metal cutting drill bit in accordance with oneembodiment of the invention;

FIG. 3 shows a perspective view of a drill bit in accordance with oneembodiment of the invention;

FIG. 4 shows a longitudinal cross section view of an exemplary drillhaving at least some common elements with embodiments shown at, e.g.,FIG. 3, in accordance with an embodiment of the invention;

FIG. 5 shows a cross section view of an exemplary drill bit having atleast some common elements with embodiments shown at, e.g., one or moreof FIG. 3-4, in accordance with an embodiment of the invention;

FIG. 6 shows a perspective view of an exemplary drill bit with at leastsome common elements from FIGS. 3-5 suited to address instances where aportion of metal to be penetrated is encountered on a surface of a rockrather than embedded within a target structure in accordance with anembodiment of the invention;

FIG. 7 shows a longitudinal cross section view of an exemplary drillbit, e.g., shown at least in part in one or more of FIGS. 3-6, inaccordance with an embodiment of the invention; and

FIG. 8 shows a cross section view of an exemplary drill bit, e.g., shownat least in part in one or more of FIGS. 3-7, in accordance with anembodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Embodiments of the invention described herein are not intended to beexhaustive or to limit the invention to precise forms disclosed. Rather,the embodiments selected for description have been chosen to enable oneskilled in the art to practice the invention.

FIG. 1. shows an exemplary method for employing an exemplary drill bitapparatus in conjunction with a hammer-drill to penetrate a portion ofmetal within a mixed material structure comprising metal and non-metalmaterials encountered during drilling operations without requiring adrill change, comprising: Step 101: identifying a task requiring rock,masonry, or concrete (or similar material) drilling with a hammer-drillin a location where a likelihood exists of encountering a portion ofmetal and where an operator or user of the drill is limited to carryingonly a single hammer-drill; Step 102: forming or providing ametal-cutting bit comprising a cylindrical body formed with a first andsecond cylindrical sections, wherein the first section comprises a firstend perpendicular to a longitudinal axis and a second end oppositethereof perpendicular to the longitudinal axis, the first sectioncomprising a shank section, wherein the second section comprises a firstend perpendicular to a longitudinal axis and a second end oppositethereof perpendicular to the longitudinal axis, the second sectioncomprising a cutting section of a selected diameter to bore a desireddiameter hole, and the first section's second end being coupled to thesecond section's first end so as to form the cylindrical body with asingle longitudinal axis. Step 103: providing the metal-cutting bit witha minimum of one protuberance or protrusion (e.g., shaft collar ormechanical stop) to the shank at a point a first distance from alongitudinal end of the first section opposite the second section,wherein the first distance is selected so as to prevent full insertionof the first section into a hammer-drill chuck, and wherein the distanceprecludes a hammer in the hammer-drill's chuck from striking thelongitudinal end of first section while the hammer-drill is inoperation; Step 104: providing the hammer-drill wherein thehammer-drill's percussive feature is always active or cannot bedeactivated by structures integral to the hammer-drill; Step 105:determining if the portion of metal to be penetrated is located on asurface of a rock, concrete, stone, masonry or similar material; if“yes,” advance to step 106, but if the portion of metal is not visible,proceed to step 107; Step 106: selecting and using in the hammer drillthe metal-cutting bit in an annular cutter embodiment (e.g., see FIG. 6)and boring until the portion of metal is penetrated; Step 107: selectinga masonry bit with a diameter selected to create a desired bore in thestructure that includes rock, concrete, stone, masonry or similarmaterial and drilling until the portion of metal within the structure isencountered; Step 108: removing the masonry bit from the hole andswitching to or substituting the metal-cutting bit, e.g., shown in FIG.3; Step 109: resuming drilling operations until the portion of metal isfully penetrated or a desired depth is achieved; Step 110: repeatingsteps 107 through 109 until a desired depth of bore is achieved.

FIG. 2 shows a simplified embodiment of an exemplary metal drillingsystem comprising a drill 201 configured to apply a torsional moment toa bit 206 coupled to the drill by a chuck 202 and configured with amechanical hammer 203 capable of striking an end 207 of the coupled bitso as to produce a repetitive axial force. The drill is not equippedwith an integral system or structure adapted for deactivating the hammerfunction where the mechanical hammer is used for a purpose ofpenetrating masonry, stone, rock, concrete or similar material. Whenintended to penetrate a portion of metal, however, a protrusion orprotuberance 204 is a coupled bit 206 at a distance from the end 207 soas to prevent contact between the drill bit's end 207 and the hammer203. For penetrating metal, a drill bit head cutting portion 205 isselected or formed having configured with geometry or cutting structureformed or selected for effectiveness in boring through metal when drivenby a torsional moment.

Referring to FIG. 3, an embodiment of an exemplary embodiment of thisdisclosure is provided comprises a cutting head 301 coupled, e.g.,welded or fixed therewith, to a drill bit (e.g., steel) assembly shaftand a Slotted Drive System (SDS) Max shank section 305 at a weld section311 opposite of end section 302. A protuberance or protrusion 308 (e.g.,shaft collar, mechanical stop, etc.) is coupled to a shank section 305of the drill bit at such a distance from the end section 302 so as toprevent a full 90 mm insertion of the SDS Max shank section 305 into aSDS Max drill chuck cavity, while still allowing for a secure fit andmechanical coupling within the chuck. Placement of the protuberance orprotrusion 308 creates a gap at the end section 302 thus preventing thedrill's hammer from striking the drill bit's end section 302.

Exemplary cutting head 301 comprises a guide cutting tip 307, aplurality of cutting edges 309, and a plurality of helical or twistflutes 303 between the cutting edges 309. The cutting head 301 includesgrooves (flutes 303) helically coiled around a rod-like inner shank thatdefine the cutting edges 309 at an intersection between flutes 303 and aface of cutting head 301 perpendicular to its axis. The flutes 303 aremilled to a depth so as to create cutting edges 309 which extendradially from an intersection of a base of the guide cutting tip 307 toan outer circumference of cutting head 301 so that a primary cuttingaction of the bit occurs across an area constituting the face of thecutting head 301. Exemplary geometry of the cutting head is optimizedfor cutting a portion of metal backed by rock, concrete, masonry, etc.material. An exemplary guide cutting tip may include a cone with anangle of one hundred and thirty five degrees at an apex. Exemplarycutting edges may be defined by a forty five degree intersection betweenthe flutes 303 and the cutting head 301.

As the inventive apparatus as shown in FIG. 3 is configured to penetratesteel backed by a rock, masonry, concrete, etc. material, when a guidecutting tip 307 exits the portion of metal, it will encounter a rock,concrete, masonry, etc. backing material before a face of the cuttinghead 301 has completed a boring operation. Due to the fact that theboring operation will be accomplished without benefit of a drill'shammer function, the backing material will present a substantialobstacle when encountered. This backing material makes it desirable tolimit a height of the guide cutting tip 307 by limiting a radius of acone so as to limit an amount of backing material which must be removedprior to the face of the cutting head 301 completing the penetration ofthe metal, allowing a reversion to a traditional masonry bit.

FIG. 3 shows an embodiment designed to cut a 2″ diameter hole in 2″ deepmaterial. An exemplary design can change to suit a required diameter andpotential material to be encountered. A number of cutters or flutedesign aspects can be adjusted depending on a desired drilling RPM andcutting material. A direction of cutting edge grooves/flutes/threads canbe “left handed” if required by an intended hammer-drill. Thisembodiment is particularly suited for instances in which a plate to bepenetrated is encountered after boring through some thickness of rock.

Referring to FIG. 4, an additional embodiment designed to cut 1½″diameter holes is shown. The FIG. 4 embodiment includes some commonstructures from FIG. 4. An exemplary cutting head 301 comprises a guidecutting tip 307 with angled faces, e.g., one hundred and thirty fivedegrees, and extending a predetermined distance, a plurality of cuttingedges 309, and flute 303 (other flutes 303 are not shown in this crosssectional figure).

Referring to FIG. 5, a different cross section view of an embodiment ofthe invention is shown. A plurality of cutting edges 309 is shown aswell as a plurality of flutes 303.

FIG. 6 shows an additional embodiment particularly suited to addressinstances where a portion of the metal to be penetrated is encounteredon a surface of a rock rather than embedded within. This embodiment ofthe invention comprises a cutting head 601 coupled, e.g., welded, to adrill steel assembly shaft and an SDS Max shank section 605 at a weldsection 611 opposite of an end section 602. A protuberance or protrusion608 (e.g., mechanical stop or shaft collar) is coupled to a shanksection 605 at such a distance from the end section 602 as to prevent, afull ninety mm insertion of the shank section 605 into a SDS Max drillchuck, while still allowing for a secure fit and mechanical coupling ofthe bit within the chuck. Forming or placement of protuberance orprotrusion 608 creates such as gap at the end section 602 as isnecessary to prevent the drill's hammer from striking the end section602. Exemplary cutting head 601 comprises an annular cutter with aplurality of cutting edges 609, and a plurality of helical or twistflutes 603 between the cutting edges 609.

FIG. 6 shows an embodiment designed to cut a 2″ diameter hole in 2″ deepmaterial. An exemplary design can change to suit a required diameter andpotential material to be encountered. A number of cutters or flutedesign aspects can be adjusted depending on a desired drilling RPM andcutting material. A direction of the cutting edge grooves/flutes/threadscan be “left handed” if required by an intended hammer-drill.

Referring to FIG. 7, an additional embodiment designed to cut 1½″diameter holes is shown. FIG. 7 is comprised of at least some commonelements as the embodiment shown in FIG. 6. Exemplary cutting head 601comprises an annular cutter with a plurality of cutting edges 609, andflutes 603 (other flutes 603 are not shown in this cross sectionalfigure).

Referring to FIG. 8, a different cross section view of an embodiment ofthe invention is shown. A plurality of cutting edges 609 is shown aswell as a plurality of flutes 603. A hollow inner diameter of an annularcutter is shown in this view.

Although the invention has been described in detail with reference tocertain preferred embodiments, variations and modifications exist withinthe spirit and scope of the invention as described and defined in thefollowing claims.

1. A method for employing an apparatus in conjunction with ahammer-drill to penetrate a portion of metal encountered during rockdrilling operations without requiring a drill change, comprising thesteps of: identifying a task requiring rock drilling with a hammer-drillin a location where a likelihood exists of encountering the portion ofmetal and where it is desirable to carry only a single drill; forming ametal-cutting bit comprising a cylindrical body formed with a first andsecond cylindrical sections, wherein the first section comprises a firstend perpendicular to a longitudinal axis and a second end oppositethereof perpendicular to the longitudinal axis, the first sectioncomprising a shank section, wherein the second section comprises a firstend perpendicular to a longitudinal axis and a second end oppositethereof perpendicular to the longitudinal axis, the second sectioncomprising a cutting section of a selected diameter to bore a desireddiameter hole, and the first section's second end being coupled to thesecond section's first end so as to form the cylindrical body with asingle longitudinal axis; and coupling a minimum of one protuberance tothe shank at a point a first distance from a longitudinal end of thefirst section opposite the second section, wherein the first distance isselected so as to prevent full insertion of the first section into ahammer-drill chuck, and wherein the distance is selected to prevent ahammer in the hammer-drill's chuck from striking the longitudinal end offirst section while the hammer-drill is in operation; providing ahammer-drill wherein the hammer-drill's percussive feature is alwaysactive; selecting a masonry bit with a diameter determined to create adesired bore in a rock; securing the masonry bit in the hammer-drill andcommencing rock drilling to establish a bore hole; continuing drillingoperations until the portion of metal is encountered; removing themasonry bit and the hammer-drill from the bore hole and decoupling themasonry bit from the hammer-drill; securing the metal-cutting bit in thehammer-drill and inserting the metal-cutting bit into the bore holeuntil contacting the portion of metal; resuming drilling operationsuntil the portion of metal is fully penetrated; removing themetal-cutting bit and the hammer-drill from the bore hole and decouplingthe metal-cutting bit from the hammer-drill; and securing the masonrybit in the hammer-drill and inserting the masonry bit into the bore holeand continuing drilling operations until a selected depth of bore isachieved.
 2. The method of claim 1 further comprising: forming thesecond section as a cylindrical cutting section having a cylindricalside wall and a longitudinal central axis, a circular cutting endopposite the first section and having a circumference when viewed froman axial direction thereof; forming a guide tip with a plurality ofcutting faces formed at an angle to the circular cutting end centeredupon the longitudinal axis, wherein the guide tip forms a cone with abase and an apex opposite, the base coupled to the circular cutting end;and forming a plurality of helical flutes on the side wall penetratingthe cylinder, extending from the cutting end toward the second section'sfirst end, and extending perpendicularly to the longitudinal axis from apoint of intersection between the guide tip and the cutting face, thecutting edges comprising an intersection of the helical flutes and thecutting face.
 3. The method of claim 2 further comprising: forming theprotuberance during a manufacturing process as an integral portion ofthe first section.
 4. The method of claim 2 further comprising: formingthe first section without the protuberance; and providing theprotuberance as a removable collar coupled to the shank by a pluralityof set screws.
 5. The method of claim 2 further comprising: forming thefirst section with an outer diameter of 18 mm; milling a portion of theshank opposite the cutting section with a plurality of open grooves anda plurality of locking segments for use in a hammer-drill with an SDSMax chuck; and forming the protuberance during a manufacturing processas an integral portion of the first section.
 6. The method of claim 2further comprising: forming the first section with an outer diameter of18 mm; milling a portion of the shank opposite the cutting section witha plurality of open grooves and a plurality of locking segments for usein a hammer-drill with an SDS Max chuck; forming the first sectionwithout the protuberance; and providing the protuberance as a removablecollar coupled to the shank by a plurality of set screws.
 7. The methodof claim 5 further comprising: forming an apex of the guide tip to forma 135 degree angle between opposing sides; and milling the helicalflutes so as to create a 45 degree angle at the intersection of thehelical flutes and the cutting face.
 8. The method of claim 6 furthercomprising: forming an apex of the guide tip to form a 135 degree anglebetween opposing sides; and milling the helical flutes so as to create a45 degree angle at the intersection of the helical flutes and thecutting face.
 9. The method of claim 1 further comprising: forming thesecond section as a cylindrical cutting section having a longitudinalcentral axis, a cylindrical exterior side wall and an opposing interiorside wall, with the exterior side wall and the interior side wallforming an open-ended, circular annular cutter body with an open cuttingend; forming a plurality of teeth circumferentially spaced about theopen cutting end configured to cut a plurality of chips; and forming aplurality of flutes extending upwardly in the outer periphery of theexterior side wall from the teeth configured to discharge the chips fromthe bore hole.
 10. The method of claim 9 further comprising: forming theprotuberance during a manufacturing process as an integral portion ofthe first section.
 11. The method of claim 9 further comprising: formingthe first section without the protuberance; and providing theprotuberance as a removable collar coupled to the shank by a pluralityof set screws.
 12. The method of claim 9 further comprising: forming thefirst section with an outer diameter of 18 mm; milling a portion of theshank opposite the cutting section with a plurality of open grooves anda plurality of locking segments for use in a hammer-drill with an SDSMax chuck; and forming the protuberance during a manufacturing processas an integral portion of the first section.
 13. The method of claim 9further comprising: forming the first section with an outer diameter of18 mm; milling a portion of the shank opposite the cutting section witha plurality of open grooves and a plurality of locking segments for usein a hammer-drill with an SDS Max chuck; forming the first sectionwithout the protuberance; and providing the protuberance as a removablecollar coupled to the shank by a plurality of set screws.
 14. A drillbit comprising: a cylindrical body formed with a first and secondcylindrical sections; wherein the first section comprises a first endperpendicular to a longitudinal axis and a second end opposite thereofperpendicular to the longitudinal axis, the first section comprising ashank section; wherein the second section comprises a first endperpendicular to a longitudinal axis and a second end opposite thereofperpendicular to the longitudinal axis, the second section comprising acutting section; the first section's second end being coupled to thesecond section's first end so as to form the cylindrical body with asingle longitudinal axis; and a minimum of one protuberance coupled tothe shank at a point a first distance from a longitudinal end of thefirst section opposite the second section, wherein the first distance isselected so as to prevent full insertion of the first section into ahammer-drill chuck, and wherein the distance is selected to prevent ahammer in the hammer-drill's chuck from striking the longitudinal end offirst section while the hammer-drill is in operation.
 15. The drill bitof claim 14 wherein the second section is comprised of: a cylindricalcutting section having a cylindrical side wall and a longitudinalcentral axis; the second section's second end comprising a circularcutting end opposite the first section, having a circumference whenviewed from an axial direction thereof; a guide tip centered upon thelongitudinal axis, forming a cone with a base and an apex opposite, thebase being coupled to the circular cutting end; the guide tip beingcomprised of a plurality of cutting faces formed at an angle to thecircular cutting end; a plurality of helical flutes on the side wallpenetrating the cylinder and extending from the cutting end toward thesecond section's first end; and a plurality of cutting edges extendingperpendicularly to the longitudinal axis from a point of intersectionbetween the guide tip and the cutting face, the cutting edges comprisingan intersection of the helical flutes and the cutting face.
 16. Thedrill bit of claim 15 wherein the protuberance is formed during amanufacturing process and is an integral portion of the first section.17. The drill bit of claim 15 wherein the protuberance is a componentnot integral to the first section and is capable of being affixed andremoved from the first section.
 18. The drill bit of claim 15 whereinthe first section has an outer diameter of 18 mm, a portion of the shankopposite the cutting section is milled with a plurality of open groovesand a plurality of locking segments for use in a hammer-drill with anSDS Max chuck; and wherein the protuberance is formed during amanufacturing process and is an integral portion of the first section.19. The drill bit of claim 15 wherein the first section has an outerdiameter of 18 mm, a portion of the shank opposite the cutting sectionis milled with a plurality of open grooves and a plurality of lockingsegments for use in a hammer-drill with an SDS Max chuck; and whereinthe protuberance is a component not integral to the first section and iscapable of being affixed and removed from the first section.
 20. Thedrill bit of claim 18 wherein the apex of the guide tip comprises a 135degree angle between opposing sides and wherein the intersection of thehelical flutes and the cutting face comprises a 45 degree angle.
 21. Thedrill bit of claim 19 wherein the apex of the guide tip comprises a 135degree angle between opposing sides and wherein the intersection of thehelical flutes and the cutting face comprises a 45 degree angle.
 22. Thedrill bit of claim 14 wherein the second section is comprised of: acylindrical cutting section having a longitudinal central axis, acylindrical exterior side wall and an opposing interior side wall; theexterior side wall and the interior side wall forming an open-ended,circular annular cutter body with an open cutting end; a plurality ofteeth circumferentially spaced about the open cutting end and aplurality of flutes extending upwardly in an outer periphery of theexterior side wall from the teeth; and the plurality of teeth beingconfigured to cut a plurality of chips which, when cut, are fed into theflutes and discharged.
 23. The drill bit of claim 22 wherein theprotuberance is formed during a manufacturing process and is an integralportion of the first section.
 24. The drill bit of claim 22 wherein theprotuberance is a component not integral to the first section and iscapable of being affixed and removed from the first section.
 25. Thedrill bit of claim 22 wherein the first section has an outer diameter of18 mm, a portion of the shank opposite the cutting section is milledwith a plurality of open grooves and a plurality of locking segments foruse in a hammer-drill with an SDS Max chuck; and wherein theprotuberance is formed during a manufacturing process and is an integralportion of the first section.
 26. The drill bit of claim 22 wherein thefirst section has an outer diameter of 18 mm, a portion of the shankopposite the cutting section is milled with a plurality of open groovesand a plurality of locking segments for use in a hammer-drill with anSDS Max chuck; and wherein the protuberance is a component not integralto the first section and is capable of being affixed and removed fromthe first section.
 27. A metal drilling system comprising: a drillconfigured to apply a torsional moment to a bit coupled to the drill bya chuck and configured with a mechanical hammer capable of ordinarilystriking an end of the coupled bit so as to produce a repetitive axialforce; the drill being configured without a means of deactivation forthe mechanical hammer; the chuck being configured to transfer thetorsional moment to the bit while simultaneously allowing free axialmovement of the bit in response to strikes by the mechanical hammer; thebit configured with a protrusion at a selected location along its shaftso as to prevent contact between an end of the bit held in the chuck andthe mechanical hammer; and a cutting portion of the bit being configuredwith a geometry selected for effectiveness in boring through metal whendriven by a torsional moment.
 28. The metal drilling system of claim 27wherein the cutting portion comprises: a cylindrical cutting sectionhaving a cylindrical side wall and a longitudinal central axis; acircular cutting end opposite the end held in the chuck, having acircumference when viewed from an axial direction thereof; a guide tipcentered upon the longitudinal axis, forming a cone with a base and anapex opposite, the base being coupled to the circular cutting end; theguide tip being comprised of a plurality of cutting faces formed at anangle to the circular cutting end; a plurality of helical flutes on theside wall penetrating the cylinder and extending from the cutting endtoward the second section's first end; and a plurality of cutting edgesextending perpendicularly to the longitudinal axis from a point ofintersection between the guide tip and the cutting face, the cuttingedges comprising an intersection of the helical flutes and the cuttingface.
 29. The metal drilling system of claim 28 wherein the cuttingportion further comprises: the apex of the guide tip comprises a 135degree angle between opposing sides; and wherein the intersection of thehelical flutes and the cutting face comprises a 45 degree angle.
 30. Themetal drilling system of claim 27 wherein the cutting portion comprises:a cylindrical cutting section having a longitudinal central axis, acylindrical exterior side wall and an opposing interior side wall; theexterior side wall and the interior side wall forming an open-ended,circular annular cutter body with an open cutting end; a plurality ofteeth circumferentially spaced about the open cutting end and aplurality of flutes extending upwardly in the outer periphery of theexterior side wall from the teeth; and the plurality of teeth beingconfigured to cut a plurality of chips which, when cut, are fed into theflutes and discharged.